1. Field of the Disclosure
There is presented an internal blow out preventer. More precisely there is presented an internal blow out preventer for use in a drill string, comprising a housing with a valve closure element and associated seals, wherein the valve closure element is configured to be moved between an open and a closed position.
2. Background of the Technology
The primary function of an Internal Blow Out Preventer (IBOP) is to shut off the mud (drilling fluid) passage on the inside of a drill string in the event well pressure exceeds limits during drilling operations on a drill rig.
However, the IBOP is also frequently used to prevent spillage of drilling fluids during each instance the top drive of the drill rig is disconnected from the drill string, e.g. each instance a new pipe or section of pipes is added to the drill string. This secondary function of the IBOP as a “mud saver” results in increased wear of the seals of the valve that has several un-desirable consequences.
One disadvantage is reduced service life of the IBOP valve, leakage when the valve is being used as mud saver after pressure testing, risk of rig downtime earlier than predicted, and more frequent need for seal replacements.
Although the use of two individual valves would solve the above problems, that solution would require additional space in the drill stem of the top drive (drilling machine), space which is not always available. The length of the drill stem located between the top drive and drill string, is limited by the travel of the top drive pipe handler, which needs to be able to grip around the box of the uppermost pipe of the drill string, just below the drill stem.
A normal set up of the drill stem between the top drive and drill string includes a cross-over sub, a remotely operated IBOP, and a second IBOP, the second IOBP being used as a closing valve at the upper end of the drill string remaining in the well and disconnected from the top drive, and a saver sub that takes the wear and damage of threads when the top drive and the drill string are connected or disconnected.
The IBOP is normally a ball valve, with the advantage that sealing has a radial symmetry, making it relatively easy to manufacture.
This disclosure relates to apparatuses intended to address at least some of the disadvantages of the prior art.